Protecting device and stretchable member thereof

ABSTRACT

A protecting device for placing an object includes two connecting members and two stretchable members. The two stretchable members are attached between the two connecting members to enclose an accommodating space. Each of the stretchable members includes a first block, a second block and two joint units. The first block includes a first linking part. The second block includes a recess portion located between two second linking parts. The two first ends of the joint unit are attached with each other and attached to the first linking part. The two second ends of the joint unit are separated with each other and attached to the second linking parts, respectively. When the stretchable members are at the retracted state, part of the joint unit is located inside the recess portion, and the joint unit is located outside the recess portion at the extended state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims priority under 35 U.S.C. §119(a)on Patent Application No(s). 103215363 filed in Taiwan, R.O.C. on Aug.27, 2014, the entire contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Technical Field

The disclosure relates to a protecting device and stretchable memberthereof, more particular to a protecting device and stretchable memberthereof for placing an object with different size.

2. Background

During the transportation of electronic device, protecting devices areused for surrounding the electronic device for protecting the electronicdevice from collision. The shape of the electronic device is different,thus protecting devices with different size are needed for theelectronic devices with different shapes. However, preparing differentmolds for manufacturing protecting devices with different sizesincreases the manufacturing cost.

Therefore, some manufacturers set a stretchable bellows-type piece inthe protecting device for the electronic devices with different sizes.However, continuous Z-shape side surface of the stretchable bellows-typepiece with variable stretching range cannot be fixed at a certain rangeto satisfy demands of users. When the stretchable piece extends toolong, the protecting piece is easily detached from the electronicdevice.

SUMMARY

One embodiment of the present disclosure discloses a protecting devicefor placing an object. The protecting device comprises two connectingmembers and two stretchable members. The two stretchable members eachare attached between the two connecting members. The two stretchablemembers and the two connecting members enclose together to form anaccommodating space which is for placing the object. Each of thestretchable members has a retracted state and an extended state. Each ofthe stretchable members comprises a first block, a second block and twofirst join units. The first block comprises a first linking part. Thesecond block comprises two second linking parts separated with eachother, and a first recess portion located between the two second linkingparts. The two first join units each comprises a first end and a secondend that are opposite to each other. The two first ends are attachedwith each other and attached to the first linking part. The two secondends are separated with each other and attached to the two secondlinking parts, respectively. Twice a length between the first end andthe second end of each first join unit is longer than a straight-linebetween the two second linking parts. When the stretchable members areat the retracted state, at least part of each of the first joint unit islocated inside the first recess portion. When the stretchable membersare at the extended state, each of the first joint unit is locatedoutside the first recess portion.

Another embodiment of the present disclosure discloses a stretchablemember having a refracted state and an extended state comprises a firstblock, a second block and two joint units. The first block comprises afirst linking part. The second block comprises two second linking partsseparated with each other, and a recess portion located between the twosecond linking parts. Two join units each comprises a first end and asecond end that are opposite to each other. The two first ends areattached with each other and attached to the first linking part. The twosecond ends are separated with each other and attached to the two secondlinking parts, respectively. Twice a length between the first end andthe second end of each of the joint units is longer than a straight-linebetween the two second linking parts. When the stretchable member is atthe retracted state, at least part of each of the joint unit is locatedinside the recess portion. When the stretchable member is at theextended state, each of the joint unit is located outside the recessportion.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description given herein below, along with the accompanyingdrawings which are for illustration only, thus are not limitative of thepresent disclosure, and wherein:

FIG. 1A is a perspective view of a protecting device with a first objectinside according to an embodiment of the disclosure;

FIG. 1B is a perspective view of a protecting device with a secondobject inside according to the embodiment of the disclosure;

FIG. 2A and FIG. 2B are side views of the stretchable member of theprotecting device at a retracted state in FIG. 1A according to theembodiment of the disclosure;

FIG. 2C is a side view of the stretchable member of the protectingdevice at an extended state in FIG. 1B according to the embodiment ofthe disclosure;

FIG. 3A is a perspective view of a protecting device with a third objectinside according to another embodiment of the disclosure;

FIG. 3B is a perspective view of a protecting device with a fourthobject inside according to the embodiment of the disclosure;

FIG. 4A is a side view of the stretchable member of the protectingdevice at a retracted state in FIG. 3A according to the embodiment ofthe disclosure; and

FIG. 4B is a side view of the stretchable member of the protectingdevice at a first extended state in FIG. 3B according to the embodimentof the disclosure.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of the disclosed embodiments. It will be apparent,however, that one or more embodiments may be practiced without thesespecific details. In other instances, well-known structures and devicesare schematically shown in order to simplify the drawing.

The following descriptions of the present disclosure, protecting device,are referring to FIG. 1A and FIG. 1B, wherein FIG. 1A is a perspectiveview of two protecting devices 1, 1′ with a first object 21 insideaccording to an embodiment of the disclosure, and FIG. 1B is aperspective view of two protecting devices 1, 1′ with a second object 22inside according to the embodiment of the disclosure. The length L1 ofthe first object 21 is smaller than the length L2 of the second object22. In addition, the distance between the protecting device 1 and 1′ isadjustable for fitting the width of the first object 21 or the secondobject 22. In this embodiment, the one protecting device 1 protects oneside of the first object 21 or the second object 22, and the otherprotecting device 1′ protects another side of the first object 21 or thesecond object 22. The first object 21 and the second object 22 are theobject protected by the protecting device. For example, the object is anelectronic device. Because the structures of the protecting device 1 andthe protecting device 1′ are similar, the following descriptions focuson the protecting device 1 and the description of the protecting device1′ will not be repeated.

The protecting device 1 comprises two connecting members 11, twostretchable members 12 and two covering members 13. The two stretchablemembers 12 are attached between the two connecting members 11. The twostretchable members 12 and the two connecting members 11 enclosetogether to form an accommodating space 10. The accommodating space 10is used for placing the first object 21 or the second object 22. Thecovering members is set on the connecting members respectively forcovering portions of the first subject 21 or the second subject 22. Eachof the stretchable members 12 includes a retracted state and an extendedstate according to the different positions and shapes of the stretchablemembers. When the stretchable members 12 are at the retracted state, asshown in FIG. 1A, the first object 21 is able to be put in theaccommodating space 10 since the size of the accommodating space 10 atthe retracted state matches with that of the first object 21. When thestretchable members 12 are at the extended state, as shown in FIG. 1B,the second object 22 is able to be put in the accommodating space 10since the size of the accommodating space 10 at the extended statematches with that of the second object 22. Furthermore, the structure ofthe stretchable members 12 are able to be applied to not only theprotecting device 1 of the disclosure but also other components withvariable lengths.

Please refer to FIG. 2A, FIG. 2B and FIG. 2C, FIG. 2A and FIG. 2B areside views of the stretchable member 12 of the protecting device 1 at aretracted state in FIG. 1A according to the embodiment of thedisclosure. FIG. 2C is a side view of the stretchable member of theprotecting device at a extended state in FIG. 1B according to theembodiment of the disclosure. The following describes the detailedstructure of the stretchable member 12. The side view of the stretchablemember 12 of the protecting device 1 at the retracted state is dividedinto FIG. 2A and FIG. 2B to avoid the symbols of the elements in onefigure becoming too complicated. The upper side and lower side of thestretchable member 12 in FIG. 2A to FIG. 2C are substantiallysymmetrical, In order to avoid the numerals in each figure becoming toocomplicated, the repeated numerals of the elements only are labeled onone side of the stretchable member 12.

The stretchable members 12 comprise a first block 121, a second block122 and two joint units 123. The first block 121 comprises a firstlinking part 1211. The second block 122 comprises two second linkingparts 1221 separated with each other by a distance and a recess portion1222 located between the two second linking parts 1221. Each of thejoint units 123 has a first end 1231 and a second end 1232 that areopposite to each other. The two first ends 1231 are attached with eachother and both of them are attached to the first linking part 1211. Thetwo second ends 1232 are separated with each other by a distance andattached to the two second linking parts 1221, respectively. Twice alength L3 between the first end 1231 and the second end 1232 is longerthan a straight-line L4 between the two second linking parts 1221. Asshown in FIG. 2A and FIG. 2B, when the stretchable members 12 are at therefracted state, at least part of each of the joint units 123 is locatedinside the recess portion 1222. As shown in FIG. 2C, when thestretchable members 12 are at the extended state, each of the joint unit123 is located outside the recess portion 1222.

As shown in FIG. 2A and FIG. 2B, when the stretchable members 12 are atthe retracted state, due to twice the length L3 between the first end1231 and the second end 1232 being longer than a straight-line L4between the two second linking parts 1221 and each of the joint units123 located inside the recess portion 1222, the joint units 123 are noteasy to leave the recess portion 1222. Thus, when the stretchablemembers 12 are at the retracted state, the distance between the firstblock 121 and the second block 122 is uneasy to vary.

When the first block 121 from the second block 122 are pulled by acertain force for separating them with each other, the shapes of thejoint units 123 are changed at a certain degree. Each of the joint units123 is pulled out of the recess portion 1222 and rotated with respect tothe first block 121 and the second block 122, which makes thestretchable members 12 transform from the retracted state to theextended state shown in FIG. 2C. Due to twice the length L3 between thefirst end 1231 and the second end 1232 being longer than thestraight-line L4 between the two second linking parts 1221, it is uneasyfor each of the joint units 123 to return to the recess portion 1222.Further, when the stretchable members 12 are at the extended state, thetwo first ends 1231 of the joint units 123 are pressed against eachother and even produce a compressed area 1231 a, which stops each of thejoint units 123 rotating with respect to the first block 121 and thenlimits the first block 121 to be pulled away from the second block 122.As a result, the distance between the first block 121 and the secondblock 122 of the stretchable members 12 at the extended state is longerthan that of the stretchable members 12 at the retracted state. Thedistance between the first block 121 and the second block 122 of thestretchable members 12 is uneasy to vary, which means the stretchablemembers 12 keep at the retracted state or the stretched state.

When the first block 121 and the second block 122 are pressed by acertain force F for making them become closer, the shapes of the jointunits 123 are changed at a certain degree. Each of the joint units 123is pressed back into the interior of the recess portion 1222 and thestretchable members 12 transforms to the retracted state shown in FIG.2A and FIG. 2B. Therefore, the distance between the first block 121 andthe second block 122 of the stretchable members 12 is uneasy to vary,which means the stretchable members 12 keep at the retracted state orthe extended state.

The manufacturing procedure of the stretchable members 12 of the thisembodiment includes that the first block 121, the second block 122 andthe two join units 123 are segmented from a main block 120 which, forexample, is made by foamed material. As shown in FIG. 2A and FIG. 2B,the main block 120 has two side surfaces 1200 that are opposite to eachother, two first cutting surfaces 1201, two second cutting surfaces1202, two third cutting surfaces 1203 and two fourth cutting surfaces1204. The join units 123 are formed by each of the first cuttingsurfaces 1201, each of the second cutting surfaces 1202, each of thethird cutting surfaces 1203 and each of the fourth cutting surfaces 1204together.

Each of the first cutting surfaces 1201 and each of the fourth cuttingsurfaces 1204 extend from the side surfaces 1200 toward an interior ofthe main block 120. Each of the second cutting surfaces 1202 and each ofthe third cutting surfaces 1203 are separated from the side surfaces1200 by a distance, respectively. The third cutting surfaces 1203 areconnected with the first ends 1231, respectively. The fourth cuttingsurfaces 1204 are connected with the second ends 1232, respectively.

When the stretchable members 12 are at the retracted state, the jointunits 123 and the first blocks 121 are divided by the first cuttingsurfaces 1201. The fourth cutting surfaces 1204 are connected with butdo not across the first cutting surfaces 1201. The joint units 123 andthe second block 122 are divided by the second cutting surfaces 1202 andthe third cutting surfaces 1203. The two third cutting surfaces 1203 areconnected with each other, and the second cutting surfaces 1202 areconnected with but do not across the third cutting surfaces 1203.

Each of the join units 123 has a first angle θ1 formed by a connectionof the second cutting surfaces 1202 and the third cutting surfaces 1203.The first angle θ1 is greater than or equal to 90 degrees and less than150 degrees. The first angle θ1 determines the compressed degree of thecompressed area 1231 a of the two first ends 1231 of the two joint units123 when the stretchable members 12 are at the extended state (as shownin FIG. 2C). The smaller the first angle θ1 is, the larger thecompressed area is. Each of the joint units has a second angle θ2 formedby a connection of the first cutting surfaces 1201 and the fourthcutting surfaces 1204. The second angle θ2 is greater than or equal to90 degrees and less than 150 degrees. When the stretchable members 12are at the retracted state, the first cutting surfaces 1201 aresubstantially paralleled to the second cutting surfaces 1202. The thirdcutting surfaces 1203 are substantially paralleled to the fourth cuttingsurfaces 1204.

The width between the two side surfaces 1200 of the main block 120 is X.When the stretchable members 12 are at the retracted state, the distancebetween a connecting position of each of the first cutting surfaces 1201and each of the side surfaces 1200 and a connecting position of each ofthe fourth cutting surfaces 1204 and each of the side surfaces 1200 isY. The length of each of the first cutting surfaces 1201 is Z. Thedistance between each of the first cutting surfaces 1201 and each of thesecond cutting surfaces 1202 is M. The length of each of the secondcutting surfaces 1202 is N. The length of each of the third cuttingsurfaces 1203 is P. The length of each of the fourth cutting surfaces1204 is Q. The distance between each of the ends of the second cuttingsurfaces 1202 and each of the fourth cutting surfaces 1204 is R. Whenthe stretchable members 12 are at the extended state, the distancebetween a connecting position of each of the first cutting surfaces 1201and each of the side surfaces 1200 and a connecting position of each ofthe fourth cutting surfaces 1204 and each of the side surfaces 1200 isT. And the protecting device 1 satisfies the following conditions:X/2<Z<2X/3; Q=Z/2; P=Q/2; Z/2<N<2Z/3; M=Q/2; Y<X/2; R=Z−N; and T=3Y/2.

Please refer to FIG. 3A and FIG. 3B, FIG. 3A, FIG. 3A is a perspectiveview of two protecting devices 3, 3′ with a third object 41 insideaccording to another embodiment of the disclosure, and FIG. 3B is aperspective view of two protecting devices 3, 3′ with a fourth object 42inside according to the embodiment of the disclosure. In thisembodiment, the length L5 of the third object 41 is smaller than thelength L6 of the fourth object 42. In addition, the distance between theprotecting device 3 and 3′ is adjustable for fitting the width of thethird object 41 or the fourth object 42. In this embodiment, the oneprotecting device 3 protects one side of the third object 41 or thefourth object 42, and the other protecting device 3′ protects anotherside of the third object 41 or the fourth object 42. Because thestructures of the protecting device 3 and the protecting device 3′ aresimilar, the following descriptions focus on the protecting device 3 andthe description of the protecting device 3′ will not be repeated.

The protecting device 3 comprises two connecting members 31, twostretchable members 32 and two covering members 33. The two stretchablemembers 32 are attached between the two connecting members 31. The twostretchable members 32 and the two connecting members 31 enclosetogether to form an accommodating space 30. The accommodating space 30is used for placing the third object 41 or the fourth object 42. Thecovering members 33 is set on the connecting members 31 respectively forcovering portions of the third object 41 or the fourth object 42. Eachof the stretchable members 32 includes a retracted state, a firstextended state and a second extended state according to the differentpositions and shapes of the stretchable members. When the stretchablemembers 32 are at the retracted state, as shown in FIG. 3A, the thirdobject 41 is able to be put in the accommodating space 30 since the sizeof the accommodating space 30 at the retracted state matches with thatof the third object 41. When the stretchable members 12 are at the firstextended state, as shown in FIG. 3B, the fourth object 42 is able to beput in the accommodating space 30 since the size of the accommodatingspace 30 at the first extended state matches with that of the fourthobject 42. Moreover, when the stretchable members 12 are at the secondextended state (not shown), the fifth object (not shown), which has alength between the length of the third object 41 and the length of thefourth object 42, is able to be put in the accommodating space 30 sincethe size of the accommodating space 30 at the second extended statematches with that of the fifth object.

Please refer to FIG. 4A and FIG. 4B, FIG. 4A is side view of thestretchable member 32 of the protecting device 3 at a retracted state inFIG. 3A according to the embodiment of the disclosure. FIG. 4B is a sideview of the stretchable member of the protecting device 3 at a firstextended state in FIG. 3B according to the embodiment of the disclosure.The following describes the detailed structure of the stretchablemembers 32. The upper side and lower side of the stretchable member 32in FIG. 4A and FIG. 4B are substantially symmetrical. In order to avoidthe numerals in each figure becoming too complicated, the repeatednumerals of the elements only are labeled on one side of the stretchablemember 32.

The stretchable members 32 comprise a first block 321, a second block322, two first joint units 323, a third block 324 and two second jointunits 325. The first block 321 comprises a first linking part 3211. Thesecond block 322 comprises two second linking parts 3221, one firstrecess portion 3222, two third linking parts 3223 and a second recessportion 3224. The two second linking parts 3221 are separated with eachother by a distance, and the first recess portion 3222 is locatedbetween the two second linking parts 3221. The two third linking parts3223 are opposite to the two second linking parts 3221 and separatedwith each other by a distance, and the second recess portion 3224 islocated between the two third linking parts 3223.

Each of the first joint units 323 has a first end 3231 and a second end3232 that are opposite to each other. The two first ends 3231 areattached with each other and both of them are attached to the firstlinking part 3211. The two second ends 3232 are separated with eachother and both of them are attached to the two second linking parts 3221respectively.

The third block 324 comprises a fourth linking part 3241. Each of thesecond joint units 325 has a third end 3251 and a fourth end 3252 thatare opposite to each other. The two third ends 3251 are separated witheach other and both of them are attached to the two third linking parts3223 respectively. The two fourth ends 3252 are attached with each otherand attached to the fourth linking part 3241. As shown in FIG. 4A, whenthe stretchable members 32 are at the retracted state, at least part ofeach of the first joint units 323 is located inside the first recessportion 3222, and at least part of each of the second joint units 325 islocated inside the second recess portion 3224. As shown in FIG. 4B, whenthe stretchable members 32 are at the first extended state, each of thefirst joint units 323 is located outside the first recess portion 3222,and each of the second joint units 325 is located outside the secondrecess portion 3224. When the stretchable members 32 are at the secondextended state (not shown), each of the first joint units 323 is locatedoutside the first recess portion 3222, and each of the second jointunits 325 is located inside the second recess portion 3224; or each ofthe first joint units 323 is located inside the first recess portion3222, and each of the second joint units 325 is located outside thesecond recess portion 3224.

The operation manner, manufacturing method and relative portions of sizeof the first block 321, the second block 322 and the two first jointunits 323 in the present embodiment are similar to those of the firstblock 121, the second block 122 and the two joint units 123 in theembodiment shown in FIG. 2A to FIG. 2C, so the similar parts are notrepeated herein. Moreover, the operation manner, manufacturing methodand relative portions of size of the third block 324, the second block322 and the two second joint units 325 in the present embodiment aresimilar to those of the first block 121, the second block 122 and thetwo joint units 123 in the embodiment shown in FIG. 2A to FIG. 2C, sothe similar parts are not repeated herein, too.

According to the protecting device with stretchable member disclosed inthe embodiments of the disclosure, twice the distance between each ofthe first ends of the joint units and each of the second ends of thejoint units is longer than the straight-line between each of the secondlinking parts of the second block, which makes the joint units uneasy toleave the recess portion and the distance between the first block andthe second block uneasy to be changed when the stretchable members arein the retracted state. Moreover, the distance between the first blockand the second block of the stretchable members at the extended state islonger than the distance between the first block and the second block ofthe stretchable members at the retracted state. The two first ends ofthe two joint units are pressed against each other, which makes thefirst block unable to be pulled away from the second block, each jointunit uneasy to return to the recess portion, and the distance betweenthe first block and the second block uneasy to be changed. Thus, thefirst block and the second block of the stretchable members have twodifferent states with different distances between the first block andthe second block. Moreover, the distance between the first block and thesecond block is uneasy to be changed when the stretchable members are atthe retracted state or the extended state for solving the detachingproblem between the protecting device and the object. Furthermore, thestretchable members with multiple blocks and joint units can have moretypes of the extended state, which the different distances between theblocks of the stretchable members fulfills the needs for the objectswith different sizes.

What is claimed is:
 1. A protecting device for placing an object,comprising: two connecting members; and two stretchable members eachattached between the two connecting members, the two stretchable membersand the two connecting members enclosing together to form anaccommodating space which is for placing the object, each of thestretchable members having a retracted state and a extended state, andeach of the stretchable members comprising: a first block comprising afirst linking part; a second block comprising two second linking partsseparated with each other, and a first recess portion located betweenthe two second linking parts; and two first join units each comprising afirst end and a second end that are opposite to each other, the twofirst ends attached with each other and attached to the first linkingpart, the two second ends separated with each other and attached to thetwo second linking parts respectively, twice a length between the firstend and the second end of each first join unit being longer than astraight-line between the two second linking parts; wherein, when thestretchable members are at the retracted state, at least part of each ofthe first joint unit is located inside the first recess portion, andwhen the stretchable members are at the extended state, each of thefirst joint unit is located outside the first recess portion.
 2. Theprotecting device of claim 1, wherein the first block, the second blockand the two first join unit are segmented from a main block, the mainblock has two side surfaces that are opposite to each other, two firstcutting surfaces, two second cutting surfaces, two third cuttingsurfaces and two fourth cutting surfaces, the first join units areformed by each of the first cutting surface, each of the second cuttingsurface, each of the third cutting surfaces and each of the fourthcutting surfaces, wherein each of the first cutting surfaces and each ofthe fourth cutting surfaces extend from the side surfaces of the mainblock toward an interior of the main block, each of the second cuttingsurfaces and each of the third cutting surfaces keep a distance from theside surfaces of the main block, the third cutting surfaces connect withthe first ends respectively, the fourth cutting surfaces connect withthe second ends respectively, wherein when the stretchable members areat the retracted state, the first joint units and the first blocks aredivided by the first cutting surfaces respectively, the fourth cuttingsurfaces and the first cutting surfaces connect with each otherrespectively, the first joint units and the second block are divided bythe third cutting surfaces respectively, the two third cutting surfacesare connected with each other, and the second cutting surfaces connectwith the third cutting surfaces respectively.
 3. The protecting deviceof claim 2, wherein each of the first join units has a first angleformed by a connection of each of the second cutting surfaces and eachof the third cutting surfaces respectively, the first angle is greaterthan or equal to 90 degrees and less than 150 degrees, each of the firstjoin units has a second angle formed by a connection of each of thefirst cutting surfaces and each of the fourth cutting surfaces, thesecond angle is greater than or equal to 90 degrees and less than 150degrees, wherein when the stretchable members are at the retractedstate, the first cutting surfaces are paralleled to the second cuttingsurfaces, the third cutting surfaces are paralleled to the fourthcutting surfaces.
 4. The protecting device of claim 2, wherein a widthbetween the two side surfaces of the main block is X, when thestretchable members are at the retracted state, a distance between aconnecting position of each of the first cutting surfaces and each ofthe side surfaces and a connecting position of each of the fourthcutting surfaces and each of the side surfaces is Y, a length of each ofthe first cutting surfaces is Z, a distance between each of the firstcutting surfaces and each of the second cutting surfaces is M, a lengthof each of the second cutting surfaces is N, a length of each of thethird cutting surfaces is P, a length of each of the fourth cuttingsurfaces is Q, a distance between each of an end of the second cuttingsurfaces and each of the fourth cutting surfaces is R, when thestretchable members are at the extended state, a distance between aconnecting position of each of the first cutting surfaces and each ofthe side surfaces and a connecting position of each of the fourthcutting surfaces and each of the side surfaces is T, and the protectingdevice satisfies the following conditions:X/2<Z<2X/3;Q=Z/2;P=Q/2;Z/2<N<2Z/3;M=Q/2;Y<X/2;R=Z−N; andT=3Y/2.
 5. The protecting device of claim 1, further comprising twocovering members set on the two connecting members for covering theobject.
 6. The protecting device of claim 1, wherein the second blockfurther comprise two third linking parts that are opposite to the twosecond linking parts and separated with each other, and a second recessportion locates between the two third linking parts, each of thestretchable members further comprising: a third block comprising afourth linking part; and two second joint units each comprising a thirdend and a fourth end that are opposite to each other, the two third endsseparated with each other and attached to the two third linking partsrespectively, the two fourth ends attached with each other and attachedto the fourth linking parts, twice a length between the third end andthe fourth end of each second joint unit being longer than astraight-line distance between the two third linking parts; wherein,when the stretchable members are at the retracted state, at least partof each of the second joint units is located inside the second recessportion, and when the stretchable members are at the extended state,each of the second joint units is located outside the second recessportion.
 7. A stretchable member having a refracted state and a extendedstate comprising: a first block comprising a first linking part; asecond block comprising two second linking parts separated with eachother, and a recess portion locating between the two second linkingparts; and two join units each comprising a first end and a second endthat are opposite to each other, the two first ends attached with eachother and attached to the first linking part, the two second endsseparated with each other and attached to the two second linking partsrespectively, twice a length between the first end and the second end ofeach of the joint units being longer than a straight-line between thetwo second linking parts; wherein, when the stretchable member is at theretracted state, at least part of each of the joint units is locatedinside the recess portion, and when the stretchable member is at theextended state, each of the joint units is located outside the recessportion.
 8. The stretchable member of claim 7, wherein the first block,the second block and the two join units are segmented from a main block,the main block has two side faces that are opposite to each other, twofirst cutting surfaces, two second cutting surfaces, two third cuttingsurfaces and two fourth cutting surfaces, the joint units are formed byeach of the first cutting surfaces, each of the second cutting surfaces,each of the third cutting surfaces and each of the fourth cuttingsurfaces, wherein, each of the first cutting surfaces and each of thefourth cutting surfaces extend from the side surfaces of the main blocktoward an interior of the main block, each of the second cuttingsurfaces and each of the third cutting surfaces keep a distance from theside surfaces of the main block, the third cutting surfaces connect withthe first ends respectively, the fourth cutting surfaces connect withthe second ends respectively; wherein when the stretchable member is atthe retracted state, the joint units and the first blocks are divided bythe first cutting surface respectively, the fourth cutting surfaces andthe first cutting surfaces connect with each other respectively, thejoint units and the second blocks are divided by the second cuttingsurfaces and the third cutting surfaces respectively, the two thirdcutting surfaces are connected with each other, and the second cuttingsurfaces connect with the third cutting surfaces respectively.
 9. Thestretchable member of claim 8, wherein each of the join units have afirst angle formed by a connection of each of the second cuttingsurfaces and each of the third cutting surfaces, the first angle isgreater than or equal to 90 degrees and less than 150 degrees, each ofthe join units have a second angle formed by the connection of each ofthe first cutting surfaces and each of the fourth cutting surfaces, thesecond angle is greater than or equal to 90 degrees and less than 150degrees; wherein when the stretchable is at the retracted state, thefirst cutting surfaces are parallel to the second cutting surfaces, thethird cutting surfaces are parallel to the fourth cutting surfaces. 10.The stretchable member of claim 8, wherein a width between the two sidesurfaces of the main block is X; when the stretchable member is at theretracted state, a distance between a connecting position of each of thefirst cutting surfaces and each of the side surfaces and a connectingposition of each of the fourth cutting surfaces and each of the sidesurfaces is Y, a length of each of the first cutting surfaces is Z, adistance between each of the first cutting surfaces and each of thesecond cutting surfaces is M, a length of each of the second cuttingsurfaces is N, a length of each of the third cutting surfaces is P, alength of each of the fourth cutting surfaces is Q, a distance betweeneach of the end of the second cutting surfaces and each of the fourthcutting surfaces is R; when the stretchable member is at the extendedstate, a distance between a connecting position of each of the firstcutting surfaces and each of the side surfaces and a connecting positionof each of the fourth cutting surfaces and each of the side surfaces isT, and the stretchable member satisfies the following conditions:X/2<Z<2X/3;Q=Z/2;P=Q/2;Z/2<N<2Z/3;M=Q/2;Y<X/2;R=Z−N; andT=3Y/2.